[FR]: Create performance learning journey

### Is there an existing issue for this?

- [X] I have searched the existing issues

### Describe the problem

We're adding performance inspection code to the app.
@JolandaVerhoef recommended creating a learning journey for this.

### Describe the solution

Let's create a learning journey.

### Additional context

_No response_

### Code of Conduct

- [X] I agree to follow this project's Code of Conduct

The issue proposes a performance learning journey alongside performance inspection code, but names no files, tests, entry points, or curriculum scope. First identify where learning journeys and performance inspection are represented in the app, then agree on the content and completion criteria. Done means the agreed journey is implemented and verified with the project's existing checks.

Written by the indexing model from the issue text.